If someone has already called shotgun or there are no seats available: "riding Henry" is the act of riding along in the bed of a truck. More creative and advanced participants will try it on the outside of a car or any vehicle other than a truck.

" man those assholes picked me up with a full crew, so I had to man up and ride Henry by myself in the back! "

"we need to get this mattress home,so someones riding Henry in the truck cuz we don't have bungie cords".